Metallurgical Double Girder Overhead Bridge Crane

Advantages of the Double Girder Design for Metallurgy

Higher Lifting Capacity: Can handle the immense weights of large ladles (often 100+ tons).

Superior Stability: Resists the side-pull and swinging forces inherent in ladle handling.

Space for Auxiliaries: Provides ample space on the trolley frame for additional safety devices, a second (auxiliary) hoist, and robust drive systems.

Better Hook Approach: Allows for a closer hook-to-ceiling distance, maximizing usable lift height in the building.

Longer Span Capability: More effective for the wide spans typical of mill buildings.

Standard vs. Metallurgical Crane

Core Components：Bearing, Gearbox, Motor, Pump

Place of Origin：Henan, China

Warranty：1 Year

Weight (KG)：2000 kg

Video outgoing-inspection：Provided

Machinery Test Report：Provided

Design：Double beam

Effectiveness：high efficiency

Operating speed：High speed operation

Stability：Anti-swing function

Color：Optional

Power Source：110V/220V/230V/380V/440V,customized

Span：7.5-31.5m

1. Bridge Components

The bridge is the primary load-bearing structure that spans the bay.

Main Girders (2): The principal horizontal beams that form the bridge. In metallurgical cranes, these are typically welded box girders for their superior strength and rigidity under heavy, dynamic loads. They are designed to resist severe twisting and buckling from hoist trolley movement and thermal stress.

End Trucks (2): The assemblies at each end of the bridge that house the wheels, bearings, and drive motors for moving the entire crane along the runway tracks.

Bridge Wheels: Extra large, forged steel wheels designed to withstand immense loads. Often, double-wheel configurations are used per end truck for higher capacity.

Bridge Drive Motors: High torque motors, typically with redundant drives (one motor per end truck) to ensure synchronized movement and provide a backup.

Bridge Brakes: Fail-safe disc or caliper brakes applied automatically in case of power loss.

Crane Buffer / Bumper: Heavy-duty shock-absorbing devices mounted on the end trucks to absorb energy in the event of a collision with the end stops.

2. Trolley Components

The trolley carries the hoist mechanism and travels along rails on top of the main girders.

Trolley Frame: A massively constructed, rigid frame that supports the hoist, all its gears, motors, and the rope drum. It's built to handle extreme shock loads from the ladle.

Trolley Drive Motor: The motor that powers the movement of the trolley across the bridge. Equipped with a fail-safe brake.

Trolley Wheels: Large, hardened steel wheels that run on the girder rails. The number of wheels is increased to distribute the immense load.

3. Hoist Unit Components

This is the heart of the metallurgical crane and where the most critical safety features are located.

Hoist Motor: A high-power, premium efficiency motor designed for severe duty cycles (e.g., NEMA Design D). It's often oversized for the application to handle shock loads and provide precise control via a Variable Frequency Drive (VFD).

Redundant Braking System:

Primary Brake: A fail-safe, spring-set, electrically released disc brake mounted on the high-speed shaft (motor shaft).

Secondary/Emergency Brake: A second independent braking system. This can be another mechanical brake on the intermediate gear shaft or, more critically, a Motorized Disc Brake or Emergency Safety Brake directly on the low-speed shaft (drum shaft). This is the ultimate failsafe to stop the load if a gearbox failure occurs.

Hoist Gearbox: A heavy-duty, multi-stage helical gearbox designed for FEM M8 or similar severe duty classification. It has a high factor of service to absorb the massive shock loads encountered in mill duty.

Drum / Rope Reeving System:

Drum: A large, grooved drum around which the wire rope is wound. It is designed with sufficient capacity and pitch to hold all the rope required for the full lift height without crushing layers.

Wire Rope: Special, high-performance rotation-resistant rope. It is often made with a independent wire rope core (IWRC) and lubricated with high-temperature grease to withstand radiant heat. It has a much higher safety factor than standard ropes.

Load Block / Hook Assembly:

Safety Hook: The main hook is a forged, high-carbon alloy steel hook with a mandatory mechanical safety latch. This latch prevents the ladle's trunnions from accidentally disengaging.

Sheaves: Large-diameter sheaves (pulleys) to reduce wear and bending stress on the wire rope.

Load Limiter / Overload Protection System: A highly accurate sensor (often a load cell integrated into the sheave pin or the rope anchorage) that constantly measures the load weight. It will sound an alarm and then cut off hoisting motion if a preset safe working load (SWL) is exceeded. This is non-negotiable on a ladle crane.

4. Electrical and Control Systems

Variable Frequency Drives (VFDs): Used for all motions (hoist, trolley, bridge). They provide incredibly smooth acceleration and deceleration, precise micro-speed control (creep speed for pouring), and protect motors from shock loads.

Programmable Logic Controller (PLC): The brain of the crane. It integrates control of all motions, monitors safety systems (brakes, overload, limits), and provides diagnostics and fault logging.

Control Interface:

Operator's Cab: Heavily insulated and air-conditioned to protect the operator from extreme heat. Equipped with large, heat-resistant windows for optimal visibility. The master switch is a dead-man switch that requires constant pressure from the operator.

Radio Remote Control: Allows the operator to control the crane from the floor, choosing the safest vantage point away from heat, fumes, and potential splash zones.

Emergency Power Down (EPD) Unit: A critical, independent system (often hydraulic or battery-powered) that engages in a total power failure. It allows the operator to slowly lower the load and prevent a "freeze-in" disaster where molten metal solidifies in the ladle.

Festoon System / Cable Reels: Heavy-duty systems to deliver power and control signals along the bridge and to the trolley. Enclosed and protected from heat and debris.

5. Specialized Protections

Heat Shields: Sheets of refractory material or special alloys mounted between the ladle and the crane structure to shield the girders, trolley, and electrical components from radiant heat.

High-Temperature Paint System: Multi-layer, epoxy-based, zinc-rich paint systems designed to withstand constant thermal cycling without peeling or degrading.

Limit Switches: Heavy-duty, fail-safe limit switches for upper travel limit (to prevent over-hoisting) and end-of-travel for bridge and trolley motions.

Sketch

Main technical

1. Unmatched Safety and Risk Mitigation

Redundant Safety Systems: The defining advantage. Dual brakes, backup drives, and overload limiters ensure a single component failure does not lead to a catastrophic accident (e.g., dropping a ladle of molten metal).

Emergency Power Down (EPD): Prevents a "freeze-in" scenario where molten metal solidifies in the ladle during a power outage, which can cause massive production delays and equipment damage.

Precise Control: Micro-speed (creep speed) capabilities allow operators to perform delicate maneuvers, like pouring molten metal into a mold, with extreme precision, minimizing the risk of spillage and splash.

2. Superior Reliability and Uptime

Ruggedized Construction: Built with heavy-duty components (FEM M8 duty class, high-grade steel) to withstand extreme shock loads, intense heat, and abrasive environments. This reduces unexpected breakdowns.

High-Temp Protections: Heat shields, refractory linings, and special paints protect vital components from degradation, extending their service life and maintaining reliability.

Designed for Severity: Every component, from the wire rope to the electrical enclosures, is selected for a harsh mill environment, leading to less downtime for repairs and maintenance.

3. Enhanced Productivity and Efficiency

Handling Massive Loads: Capable of lifting and moving extremely heavy loads (often hundreds of tons) that are impossible to handle by any other means within a mill.

Process Integration: They are not just for moving items; they are integral to the metallurgical process itself (e.g., furnace tapping, pouring into continuous casters). Their smooth control is essential for product quality and process efficiency.

Flexibility: A single crane can serve multiple functions within its operating area, such as charging a furnace, moving molten metal, and handling slag pots.

4. Long-Term Economic Value (Lower Total Cost of Ownership)

Durability: While the initial cost is high, their robust construction leads to a much longer operational lifespan than standard cranes under the same conditions.

Reduced Downtime Costs: The immense cost of stopping a production line (e.g., a steel melt shop can lose tens of thousands of dollars per hour) makes the reliability of a metallurgical crane a sound investment. Preventing a single major accident can pay for the crane's premium features.

5. Improved Operator Control and Ergonomics

Multiple Control Options: Options like insulated, air-conditioned cabs and radio remote controls allow operators to work from the safest and most ergonomic position, away from heat, fumes, and potential danger zones.

Smooth Operation: VFD controls ensure smooth acceleration and deceleration, reducing load swing and making precise placement easier, which reduces operator fatigue.

These cranes are purpose-built for specific, high-stakes tasks in metal production and foundries.

Primary Application: Molten Metal Handling

Ladle Transportation: The most critical application. Moving ladles filled with molten iron or steel from the melting furnace (e.g., Basic Oxygen Furnace, Electric Arc Furnace) to the next processing stage.

Furnace Tapping: Positioning an empty ladle beneath the furnace tap hole to receive the flow of molten metal.

Pouring: Transferring molten metal from a transport ladle into:

Continuous Casting Machine: Pouring into a tundish to begin the casting process.

Ingot Molds: Pouring into molds to form ingots.

Pattern Molds: In foundries, pouring into molds to create castings.

Secondary Applications: Hot Material and Process Handling

Furnace Charging: Loading raw materials (scrap metal, pig iron, alloys) into the melting furnace.

Slag Pot Handling: Lifting, transporting, and tipping large pots filled with the molten slag byproduct of the smelting process.

Hot Metal Transfer: Moving containers of molten metal between different process areas (e.g., from a blast furnace to a torpedo car or mixer).

Hot Stock Handling: Handling still-hot finished products like steel slabs, coils, or billets from the casting or rolling process to cooling beds or storage.

The manufacturing process of a QDY metallurgical casting bridge crane involves strict quality control and specialized engineering to ensure durability, heat resistance, and safety. Below is a step-by-step breakdown of the production procedure:

1. Design & Engineering

Load & Environment Analysis – Calculations for lifting capacity (5–500+ tons), span, and heat resistance.

CAD/3D Modeling – Structural design, stress simulations (FEA), and compliance with ISO, FEM, or GB standards.

Customization – Optional features (explosion-proofing, insulated hoists, automation) are integrated.

2. Material Selection & Preparation

Main Girders & End Carriages – High-strength steel (Q345B, Q460C) or heat-resistant alloy steel.

Wire Ropes & Hooks – Special heat-treated alloy steel (for molten metal handling).

Electrical Components – High-temperature-resistant cables, motors, and insulation materials.

3. Fabrication of Key Components

A. Bridge Girder Construction

Cutting & Welding – CNC plasma/laser cutting for precision; submerged arc welding (SAW) for high-strength joints.

Heat Treatment – Stress-relieving annealing to prevent deformation.

Machining – Drilling, milling, and surface grinding for assembly accuracy.

B. Hoist & Trolley Assembly

Hoist Drum & Gearbox – Machined for smooth operation; tested under 1.25x rated load.

Heat-Resistant Brakes – Dual-disc or electromagnetic brakes for fail-safe holding.

Ladle Hook & Safety Latch – Forged and ultrasonically tested for cracks.

C. End Trucks & Runway System

Wheel & Rail Machining – Hardened steel wheels for long wear life.

Drive Motors & Reducers – Equipped with anti-skid mechanisms for heavy loads.

4. Electrical & Control System Integration

Festoon/Conductor Bar System – For power supply along the runway.

Variable Frequency Drives (VFDs) – For smooth speed control and energy efficiency.

Safety Circuits – Overload sensors, limit switches, and emergency stop.

Operator Controls – Pendant, cabin, or remote/automated systems.

5. Surface Treatment & Corrosion Protection

Sandblasting (SA 2.5 Grade) – Removes rust and improves paint adhesion.

High-Temp Paint/Coating – Zinc-rich primer + heat-resistant topcoat (up to 800°C).

Critical Component Insulation – Ceramic fiber or refractory coatings on hooks and ropes.

6. Assembly & Testing

A. Pre-Assembly Checks

Dimensional inspection of girders, trolley, and end carriages.

Alignment of runway rails and crane tracks.

B. Load Testing (Per ISO 4310 / GB Standards)

No-Load Test – Checks motor, brake, and travel functions.

Static Load Test – 1.25x rated capacity for 10+ minutes.

Dynamic Load Test – 1.1x rated capacity with repeated movements.

Emergency Brake Test – Verifies fail-safe mechanisms.

C. Heat Resistance Validation (For Foundry Cranes)

Simulated high-temperature exposure (if required).

7. Packaging & Delivery

Disassembly (if needed) – For large cranes, components are shipped separately.

Anti-Corrosion Packaging – VCI film or desiccant for overseas transport.

Documentation – Manuals, test reports, and certifications (CE, ISO, GOST, etc.).

8. Installation & Commissioning (On-Site)

Runway alignment and crane reassembly.

Final load testing and operator training.

Workshop view:

The company has installed an intelligent equipment management platform, and has installed 310 sets (sets) of handling and welding robots. After the completion of the plan, there will be more than 500 sets (sets), and the equipment networking rate will reach 95%. 32 welding lines have been put into use, 50 are planned to be installed, and the automation rate of the entire product line has reached 85%.